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Topic Review (Newest First)

02-06-2013 02:53 PM

Powder Coater

Power Coating Primer

Powder Coating Primers are needed for adhesion problems, uneven surface quality and orange peel look. Their are two major type of powder coating primers normal and out-gas stopping primer. Out gas primer is best used on aluminum and cast metal parts as micro cracks in cast metal hold gas and impurity's.

So yes use powder coating primers when high strength is needed or when you have adhesion problems.

<a******************************..

02-07-2004 09:39 AM

willys36@aol.com

I erase my PMs as soon as I act on them to keep the directory open - fills up pretty fast and is of limited size.

Lab Metal is similar to bondo in function but different in chemistry. It doesn't use a catalyst like 2-part bondo does. It hardens by evaporation of solvents only.

I'm 'expert' in powder coating like I am 'expert' in roc 'n roll music - great audience material!! Not sure what would do that but since the coating is the same plastic all the way through and the stain you describe sounds like a superficial surface blemish, can you just polish it out? What does your vendor say about it?

02-06-2004 11:49 PM

bullheimer

gee 36 you only have 2 pm's you must be a newbie. that stuff sounds alot like bondo. only for ovens. is that a real 36? since you know so much about p.c'n. what would cause a huge oil lookin run, but after you bring it home. like a drip of hydrochloric acid, exceptit isnt?

hey newbie boy. you know anything @ oil?

02-05-2004 10:24 AM

willys36@aol.com

No haven't used it myself, I just became aware of it within the past couple of weeks. However, the description sure sounds like it is miracle bondo and it was developed in the first place for the powder coater industry so I am pretty sure they will cure it for you during their treatment. The product specs say it cures @ 475F for 1hr which is right where the PC treatment is done.

Just talked to my powder coater and asked him about Lab Metal. he said they have used it and it works great. They even used it to build up door sills that were not going to be powder coated on a hot rod project where welding or regular bondo was impractical.

Tips he gave were -

- Do your sanding and finishing soon after it sets up because when it has cured very long it is as hard as steel!

- Apply it in thin layers and let it dry well between. If applied too thick and not allowed to evaporate the solvents, when powder coated there will be a rim of pinholes in the final finish around the feathered area where the trapped solvents out-gas.

He also mentioned that you can use slow cure JB Weld under powder coating, but it is pretty runny and hard to work compared to Lab Metal.

02-05-2004 10:13 AM

Thom Laybourne

OK

Hey, willys. I will have to try so of that. We are stripping a 46 PU to frame and that should come in handy. It will be a few months away, but maybe I will remember to post a remark or two about it. Have you ever used it? Just spread it on and sand smooth? Let the PC cure it? I don't have an oven, so hope it works that way. You are always a book of knowledge.

hr41pearl

02-05-2004 09:41 AM

willys36@aol.com

Use this stuff on the base metal like you would use bondo under a paint job for a perfect surface before powder coating. This will stand up to 1000F temperatures - the 400F that the coater use is the recommended curing temperature.

Ask them what they recommend you do to get rid of any blemishes in the frame. Will the PC smooth everything out or do you need to grind it down? I like mine smooth, so I grind them down. But they may have some new way that is less aggressive to the metal. Be interested in knowing.

hr41pearl

02-05-2004 01:43 AM

gsrokmix

Very interesting info guys! I am blasting the parts at home to save money as well as to see the real condition of things under almost 40 years of dirt and scale. I have checked with a couple of other PC'ers since my initial post and they said that they do not primer and that coating with an oil to prevent rust after blasting was ok since they were going to give the parts a bath. I am going to take a ride to a couple of these shops before I give them any parts just so I can scope them out more closely.

I finally got hold of my powder coater and asked him about the idea of primer. He said 99.999% of the time there is no need. Some less reputable coaters avoid the expensive sandblast-to-white-metal step and dip the parts in a phosphoric acid etch solution hoping for a good bond of the melted plastic.

There are proprietary industrial plastic coatings that 'require' precoating with a phenolic epoxy plastic and final coating of the outer surface. Funny thing, California outlawed the phenolic epoxy primer and the vendor issued a product bulletin that said, "Shazam, we just discovered that the outer coating works great without the primer so keep buying our stuff!".

My guy started getting questions from new customers, "Do you metal spray before powder coating?" Strange request until he found out that some guy in northern California was doing that. Not a good idea. Although metal spray does have a VERY rough and porous surface and would bond extremely well to the plastic, it sometimes does not bond well to the base metal and flakes off. Also it would at least double the cost of the final job with no significant improvement in performance. Metal spray is old tech as far as decorative coatings go.

Finally, my guy says that for some hard to cover colors, he will 'prime' with a similar easy to cover color, then put on the final color.

For our purposes, just take your grungy parts to the coater and ask for their standard blast & coat service.

01-29-2004 06:02 PM

Twin_Turbo

a good powdercoater will not only tank it to clean but also dip it for a zinc phosphate coating. My brother is a coating engineer and he has lots of experience with powdercoating systems and development and for a top notch result it's the best way to go. Chances are that if you deliver your parts blasted they will clean adn dip it. But, do not use anything that comes in a can.

When powdercoating galvanized parts the zinc phosphate is an absolute must.

01-27-2004 12:53 PM

Thom Laybourne

Dont

I have had several frames PCd and they want you to leave them unfinished. They tank for a good clean and it will remove rust. Better to pay attention to SMOOTHING areas. Powder Coat will level, but not fill in. Use a good Scotch Brite wheel and get it flat. I took about three months out side cleaning the frame and scotched it smooth. They tanked it and did a great job.

hr41pearl

01-26-2004 08:18 PM

adtkart

I wouldn't be near as concerned about them charging to sand blast the part, as I would them blaming me for their work failing later.

01-26-2004 06:09 PM

bullheimer

i thought it only went on bare metal as well. in either case, i would NOT put any primer on "for them". if it's the wrong kind or they dont know what it is they will sandblast it off and charge you for the sandblasting.

01-26-2004 08:40 AM

willys36@aol.com

Since the whole idea of powder coating is to have a pristine chemically and mechanically clean sand blasted white metal surface on which to melt the plastic powder, I can't imagine what kind of primer would enhance the process. I have my pickup frame, running gear, fender wells, and a bunch of other parts down at my 'coaters right now. I'll ask him if he knows anything about that. He has pretty good credentials, does a ton of oil field and refinery work such as the 6,000psi refinery heat exchanger enclosures he was doing when I dropped off my frame.

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